1. Forces

1.1 Definitions

A force is a physical interaction that can be applied to an object and cause it to accelerate. In physics, a force is defined as a vector that measures the intensity, direction and nature of the interaction. Forces can be of different kinds (mechanical, electromagnetic, gravitational, nuclear, etc.) and can be exerted by one object on another or on itself.

It is defined by a direction, an intensity or magnitude, a sense, and a point of application. Forces can also be actions distributed over lines, surfaces or volumes: we therefore speak of force density.